There are generally two types of electronic cameras, those that produce motion images and those that produce still images. Typical motion cameras include motion video cameras and computer-connected cameras like the Color QuickCam.TM. camera sold by the Connectix Corporation, and typical still cameras include the Kodak line of digital cameras, including the DC40 and DC50 cameras sold by the Eastman Kodak Company. With motion video cameras, it is typical to input images to a computer via a "frame grabber" board. In this case still images and motion images are captured using a single field or frame of the video. Therefore, the processing for motion and still images, performed in hardware inside the camera, is the same whether still or motion images are captured.
With electronic still cameras, the output processing is typically oriented toward still images, since still image capture is the object of the camera. U.S. Pat. No. 5,402,170, entitled "Hand-manipulated Electronic Camera Tethered to a Personal Computer", describes a digital still camera tethered to a computer for capturing an image and providing the captured image to the computer for storage therewith. Capture of images can be initiated from the camera, but its shutter button, which is controlled pursuant to a status signal from the computer, is used only to initiate the capture of still images.
If the electronic still camera provides another mode, it is typically subsidiary to the main purpose. For example, in U.S. Ser. No. 08/367,399, filed Dec. 30, 1994 (entitled "Electronic Camera Having Dual Modes for Composing and Capturing Still Images" and assigned to the same assignee as the present invention), an electronic still camera is described in which a motion mode is used to provide a "preview" image on an LCD viewfinder prior to still mode capture. The camera does not output the motion image data, but simply displays the motion data on the LCD display. Being part of its fixed signal processing, the camera does not allow the user to affirmatively elect between the motion and the still mode.
U.S. Pat. No. 5,301,244, entitled "Computer Input Scanner Incorporating Multiple Scanning Modes", describes a film scanner useful as an input device for a computer. The film scanner is operable in two modes: the first mode is a low resolution monochrome prescanning mode used for composing (zooming and cropping) the image, and the second is a high-resolution color sequential mode in which three successive high resolution color scans are obtained. Two user-controlled switch functions on the scanner are used: one to continuously capture low resolution frames in the prescan mode, and the second to initiate a high-resolution scan. These switch functions, however, always perform the same task, that is, either to initiate prescan or to capture a high resolution image.
While describing two modes of operation in some cases, the prior art does not allow flexibility in user selection of these modes, or in the communication of mode information between a host computer and the camera. As a result, the functionality of user-controlled switches, e.g., the shutter button, remains fixed.